1. Field of the Invention
The present invention relates to an electronic device that has a substrate mounted with an electronic circuit and accommodated in a housing.
2. Description of the Related Art
Recently, various types of mobile personal computers (abbreviated as PC hereinafter) have come into widespread use. One such a PC is a so-called notebook PC composed of a main unit incorporating an arithmetic circuit and having a keyboard on the front surface thereof and a display unit having a display screen and being capable of folded onto the main unit. Another type of such a PC is a pure-tablet (slate) PC that incorporates an arithmetic circuit and has a display screen on the top surface thereof, to which a keyboard is optionally externally connected.
Such mobile PCs are made thinner to reduce the overall size and weight while maintaining the required display screen size, whereas the mobile PCs have more capabilities to meet various needs. Thus, multiple electronic components mounted on the substrate causes increase in the temperature of the housing, and for this reason, a typical mobile PC incorporates a cooling fan to decrease the increased temperature of the housing. For example, in PCT International Application Publication No. WO03/001860, there is proposed the electronic equipment including a cooling fan removably attached to the equipment, so that the cooling fan can be removed when cooling is not necessary.
In Japanese Patent Application Publication No. 2000-232276, there is proposed the electronic equipment adapted to reduce noise generated by a fan. Additionally, Japanese Patent Application Publication No. 2000-194454 proposes the electronic device having the structure which prevents heat of air blown out from an exhaust hole of a motor fan from being transferred to a housing.
It should be noted here that an air cooling fan is more likely to be out of order compared with other components as it includes a moving part. Meanwhile, as a heat generating component such as a CPU is often attached onto the substrate fixed in the casing, the air cooling fan needs to cool the heat generating component effectively.
For this reason, it is desirable to dispose the air cooling fan near the heat generating component. However, when replacing the cooling fan disposed near the heat generating component, the substrate needs to be removed. As the substrate is often connected to several components, the removal of the substrate is not easy, which deteriorates workability of replacing the fan.
Additionally, in order to prevent interference between the fan and the substrate, it may be contrived that a heat transfer component intervenes between the fan and the substrate such that the heat transfer component transfers heat from the heat generating component on the substrate to the fan outside the substrate for air cooling. However, this causes the fan to interfere with the heat transfer component. The heat transfer component needs to be attached to the heat generating component so as to transfer heat, for example, using a thermal adhesive. Thus, replacing the fan requires removal of the adhesive as well as the heat transfer component and again attachment of the heat transfer component to the heat generating component, which also deteriorates workability of replacing the fan.